Not sure if it'll help or not, but get these instead of genuine Ford if you do decide to change it. NTK make them for Ford, these just don't have the Ford stamp, and are heaps cheaper. http://www.ngk.com.au/oxygen-sensors-part-finder?PageMode=Results&Make=FORD&Model=Falcon+BF++XR-6T&Capacity=4.0L&Year=10%2F05+-+02%2F08&Engine=&Engine=Barra+240T%2C+6FPAAAJG6+Cyl+DOHC+TMPFI+24V+240+ http://www.carpartsaustralia.com.au/product_info.php?products_id=11652 http://www.carpartsaustralia.com.au/product_info.php?products_id=11651